Assessment of Itch and Pain in Animal Models and Human Subjects.

For the past century, scientists have developed a variety of methods to evaluate itch and pain in both animal models and human subjects to throw light on some of the most important pathways mediating these unpleasant sensations. Discoveries in the mechanisms underlying itch and pain in both physiological and pathological conditions relied greatly upon these studies and may eventually lead to the discovery of new therapeutics. However, it was a much more complicated job to access itch and pain in animal models than in human subjects due to the subjective nature of these sensations. The results could be contradictory or even misleading when applying different methodologies in animal models, especially under pathological conditions with a mixed sensation of itch and pain. This chapter introduces and evaluates some of the classical and newly designed methodologies to access the sensation of itch and pain in animal models as well as human subjects.